:root {
  color-scheme: light;
  --bg: #f6f7f4;
  --surface: #ffffff;
  --surface-soft: #eef4ef;
  --text: #1d2520;
  --muted: #68736c;
  --border: #dbe2dc;
  --accent: #24745a;
  --accent-strong: #15553f;
  --accent-soft: #dff0e9;
  --warn: #8a5a16;
  --wrong: #b84242;
  --right: #23704a;
  font-family: "Microsoft YaHei", "PingFang SC", "Noto Sans CJK SC", system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
}

button,
input {
  font: inherit;
}

.site-header {
  align-items: end;
  border-bottom: 1px solid var(--border);
  display: flex;
  gap: 24px;
  justify-content: space-between;
  padding: 28px clamp(16px, 4vw, 48px) 22px;
}

.eyebrow {
  color: var(--accent);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0;
  margin: 0 0 8px;
}

h1 {
  font-size: clamp(26px, 4vw, 42px);
  line-height: 1.12;
  margin: 0;
}

.stats {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  justify-content: flex-end;
}

.stats span,
.badge {
  background: var(--surface-soft);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--accent-strong);
  font-size: 13px;
  font-weight: 700;
  padding: 6px 10px;
  white-space: nowrap;
}

.layout {
  display: grid;
  gap: 22px;
  grid-template-columns: minmax(220px, 280px) minmax(0, 1fr);
  padding: 22px clamp(16px, 4vw, 48px) 48px;
}

.panel {
  align-self: start;
  position: sticky;
  top: 16px;
}

.tabs {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  display: grid;
  gap: 4px;
  grid-template-columns: repeat(3, 1fr);
  padding: 4px;
}

.tab {
  background: transparent;
  border: 0;
  border-radius: 6px;
  color: var(--muted);
  cursor: pointer;
  padding: 9px 10px;
}

.tab.is-active {
  background: var(--accent);
  color: #ffffff;
  font-weight: 700;
}

.search {
  display: grid;
  gap: 8px;
  margin-top: 16px;
}

.search span {
  color: var(--muted);
  font-size: 13px;
}

.search input {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  outline: none;
  padding: 11px 12px;
  width: 100%;
}

.search input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}

.hint {
  color: var(--muted);
  font-size: 14px;
  line-height: 1.7;
  margin-top: 16px;
}

.questions {
  display: grid;
  gap: 16px;
}

.loading,
.question-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.loading {
  color: var(--muted);
  padding: 24px;
}

.question-card {
  padding: clamp(16px, 3vw, 24px);
}

.question-card.is-hidden {
  display: none;
}

.question-head {
  align-items: center;
  display: flex;
  gap: 10px;
  margin-bottom: 12px;
}

.number {
  color: var(--muted);
  font-size: 14px;
}

h2 {
  font-size: 19px;
  line-height: 1.55;
  margin: 0 0 16px;
}

.options {
  display: grid;
  gap: 10px;
}

.option {
  align-items: start;
  background: #fbfcfb;
  border: 1px solid var(--border);
  border-radius: 8px;
  cursor: pointer;
  display: grid;
  gap: 10px;
  grid-template-columns: auto 1fr;
  line-height: 1.55;
  padding: 12px;
}

.option input {
  accent-color: var(--accent);
  margin-top: 4px;
}

.option.is-selected {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.option.is-correct {
  border-color: var(--right);
}

.option.is-wrong {
  border-color: var(--wrong);
}

.option-key {
  font-weight: 700;
  margin-right: 4px;
}

.actions {
  display: flex;
  gap: 10px;
  margin-top: 18px;
}

.submit,
.reset {
  border-radius: 8px;
  cursor: pointer;
  min-height: 40px;
  padding: 9px 14px;
}

.submit {
  background: var(--accent);
  border: 1px solid var(--accent);
  color: #ffffff;
  font-weight: 700;
}

.reset {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
}

.result {
  border-radius: 8px;
  font-weight: 700;
  line-height: 1.6;
  margin: 14px 0 0;
  padding: 10px 12px;
}

.result:empty {
  display: none;
}

.result.is-right {
  background: #e1f3e9;
  color: var(--right);
}

.result.is-wrong {
  background: #f9e3e3;
  color: var(--wrong);
}

.result.is-uncertain {
  background: #f8efd9;
  color: var(--warn);
}

@media (max-width: 820px) {
  .site-header {
    align-items: start;
    display: grid;
  }

  .stats {
    justify-content: start;
  }

  .layout {
    grid-template-columns: 1fr;
  }

  .panel {
    position: static;
  }
}